Telephone system



Feb. 19 1924. I I 1,483,956

J. F. TOOMEY TELEPHO NE SYSTEM Filed Nov, 8, 1921 sheets sheet 1 I NVENTOR LII/230mg ATTORNEY Patented Feb. 19, 1924.

I UNITED STATES JoHN F. 'rooMEY, on EW YORK, N. in, ASSIGNO-B. TO AMERICAN TELEPHONE AND TELEGRAPH ooMrANY, A CORPORATION on NEW YORK;

TE Ern-oN'E SYSTEM.

Application filed November 8, 1921. Serial No. 513,701.

To all whom, it may concern:

Be it known that I, JOHN F. TooMEY, residin at New York, in the county-of New Fork and State of New York, have invented certain Improvements in Telephone Systems, of which the following is a specification.

This invention relates to telephone ex change systems, and more particularly to such systems in which telephone lines terminating at different telephone exchanges may be interconnected by means of a link or connecting circuit. Theobject of this invention is the production of a link circuit by means of which the work of establishing connections between telephone lines may be greatly simplified.

In accordance with one feature of the invention, ringing current is applied to the called subscribers station when connection is established therewith and at predeter trunk circuit; and Fig. 2 shows a link or cord circuit, which embodies certain features of the invention, and which is adapted to operate with the trunk circuit indicated in Fig. 1.

' Referring to the drawings, there is shown at A a telephone station connected with a telephone line which terminates at a central ofiice. At B is shown atrunk circuit which may be used to connect with a telephone line extending to a telephone station, such as A. O represents a link or cord circuit which may be used to interconnect telephone stations through the medium ofa trunk circuit such as that indicatedat B.

Assuming that after a connection has been established between two central ofiices, in the usual manner, as for instance, by inserting plug P of link circuit!) in jack J of trunk B, it being understood that the opposite plug. P? of the link circuit has been inserted intoa toll trunk of the customary type, and plug P of trunk B into jack J of the line leading to the subscribers station A, the following circuit will be closed: from ground, sleeve contacts of jack J and plug P, winding of relay 1,

conductor 2, lower winding of relay 3, conductor 4:, winding of relay 5 to battery. The closing of this circuit causes the energizetion of relay 5. Relay 1 being marginal does not operate at this time. The operation of relay 5'closes a circuit through its 'make contact from battery, conductor 7, winding of relay 8, normal contact of relay 9, conductor 10, lower normal contact of relay 11 to ground.v The closing of this circuit operates relay 8 momentarily and prevents prematureringing. I

The connection of lug P and jack J also closes a circuit from ground and battery through the windingsof relay- 12 of trunk B, conductors 13 and 1 1, upper and lower normal contacts of relay 15', respectively, tip and ring conductors of trunk B, tip and ring contacts of jack J and plug P, normal contacts of key K, back contacts of relay 11,

conductors 16 and 17 windings of coil 18,

conductors 19 and 20, including winding of relay 9. Theclosing of this circuit'operates relays 12 and 9. Theoperation of relay 9 closes a circuit from ground, lower normal contact of relay 11, conductor 10, make contact of relay 9, lower normal contact of relay .21, conductor 22, normal contacts of relays 23 and 8, this relay being now deenergi'zed, windingof slowrelease relay 2 1, lefthand winding of relay 25, conductors 26 and 7 closed contact of relay 5, to battery. The

"closing of this circuit operates relays 24 and 25, and the operation of the latter relay closes a locking'circuit through its righthand make contact and winding from,

ground, conductors 26 and 7 closed contact of relay 5 to battery. The operation of relay 24 closes a circuit through its lefthand make contact from ground, conductor 27 filament of lamp 28, back contact of relay 29, to battery, thereby causing the lighting of supervisory lamp 28. The 'operationof relay 24: also closes a circuit from battery, winding of relay' 11, conductor 30,

right-hand closed contact of relay :24,

through interrupter 31 to vground. The closing of this circuit operates relay 11 intermittently underthe control of interrupter 31. Eachtime therelay 11 operates, ringing current is transmitted from source 32, through winding of relay 29, conductor 34, lower make contact of relay 11, lower- The closure of this circuit causes relay 29 to operate intermittently under control of relay 11. resistance 33 is included in series with the Each time relay 29 operates, the

supervisory lamp:28, dimming it at regular intervals. The flickering of this lamp indioates to the operator at G that ringing is in progress on that particular cord. During the 'ringing interval relay 15 of trunk '13 operates, as will appear later, and the circuit wherebyr'elay 9 was energized is broken and thisrelay releases, but relay 24 remains operated during the ringing period and the silent period. During the ringing per-iod 'C closes a circuit through its make contact from ground, conductor 36, winding of relay 37, conductor 38, lower winding of relay 15 to battery. The closing of this circuit operates relays 37 and 15, and as relay 40 was operated upon the connection of plug P and jack J bya circuit from ground through the sleeve contacts ofsaid jack and plug, winding of relay 40 to battery, ringing current will be impressed upon the line from source 41, over the ring contacts of said plug and jack, through the ringer at station A and return by way of the tip contacts of said jack and plug to ground, through the lower closed contact of relay 37. The station A will be thus signaled automatically at predetermined intervals until it answers or until the operator abandons the call.

When-the subscriber 'at station Aresponds to said signal by removing the receiver from its hook, ringing jcurrent' will be automatically disconnected in 13116 following manner Relays 39 willbe operated :by' a circuit through its winding .from grbund and" battery over the tip'fa'nd ring-conductors :of

trunk B, including like contacts of plug P and" jack J over the line and through the switch-hook at station A in a well understoodrmanner. The operation of relay 39 closes a circuit from battery, lower winding of relay 15, make contact of relay 39, upper winding of relay 15, make contact of relay 12 to ground. The closing of this circuit causes the operation of relay 15 which opens the circuit previously traced whereby relay 9 of link circuit C was operated, causing this relay to release permanently. The re lease of relay 9 closes a circuit from ground, lower back contact of relay 11, winding of relay 8, conductor 7, make contact of relay 5 to battery. The closing of this circuit causes the operation of relay 8, thereby opening the circuit by which relay 24 was energized causing it to release. The release of relay 24 closes a circuit through its back contact from ground left-hand make contact of relay 25, this relay being maintained operated by means of the locking circuit previously described, winding of relay 23 to battery thereby operating relay 23. The release of relay 24 disconnects the ground through interrupter 31 from relay 11, thereby preventing further energiz ation thereof. The release of relay 11 disconnects ringing current from source 32 through relay 29 thereby releasing the latter relay." The release of relay 11 causes the release of relay 35 of trunk B, which, in turn, provides for the release of relay 37. The release of 24 also opens the circuit which supervisory lamp 28 was lighted, and the extinguishing of this lamp indicates to the operator at C thatthe called station Ahas answered.

If the called subscriber at station A, after answering the call, desires to signal the operator, and'moves the switch-hook up and down, relay 39 of trunk 13 will operate and release, thereby opening and closing the'energizi'ng circuitpreviously described in con nection with relay 9, causing this relay to operate and release. Each time relay 9 operates, a circuit will be closed from ground, conductor 10, make contact of relay 9, normal contact of relay 21, conductor 22, make contact of relay 23, filament of'lamp 28, contact of relay 29 to battery. The intermittent opening and closing of this circuit causes supervisorylamp 28 to flash, and the operator C by operating key K may estab- 'lish a talking connection with station A in a Well-known manner.

l/Vhen the subscriber at station A restores the receiver to its hook,'relay 39 will be deenergized and in turn will deenergize relay 15. The release of relay 15 will causethe operation of relay 9 over the circuit previously outlined. The operation of relay 9 will close a circuit from ground, lower normal contact of relay 11, conductor 10, make contactof relay 9, normal contact of relay 21, conductor 22, make contact of relay 23,

filament of lamp 28, normal contact of relay 29 to battery. The closing of this circuit will light the lamp 28 as a disconnect signal, whereupon the operator will remove plug P from jack J and the entire circuit will be restored to normal. l

If, instead of disconnecting, the operator at C desires to re-ring the called subscriber at station A, after said station has once answered and then hung up, the operator can do so by removing plug P from jack J and then re-inserting said plug in said jack. This starts the whole ringing cycle, previously explained, over again.

The link circuit C is also adapted for use in through toll connections. In such connections marginal relay 1 will also operate, in addition to the operation of relay 5 previously referred to, owing to the low resistance connected with the jack sleeve of the toll line (not shown). lay 1 will close the circuit through its make contact from ground, winding of-relay 21 to battery, thereby operating relay 21. The operation of relay 21 disconnects the energizing circuit of relay 9 from across the tip and ring conductors of the link circuit and removes the machine ringing equipment from the control of relay 9, giving that relay direct control over the supervisory lamp 28 instead. The link circuit C is provided with the ordinary manual ringing keys such as that indicated at K for ringing on such connections.

Although the improved link circuit is herein shown and described as connectedwith a trunk circuit by way of illustration, it will be understood that in practice intermediate circuits may be employed in addition to said link circuit and said trunk circuit.

What is claimed is:

1. In a telephone system, a subscribers line terminating in a line jack at a central office, a link circuit, a trunk circuit for interconnecting the subscribers line and link circuit, a source of ringing current associated with the trunk circuit adapted to be impressed upon said subscribers line, signaling means associated with said link circuit operable in a characteristic manner by the application of ringing current to said subscribers line, and means associated with said link circuit responsive to the closure of said subscribers line for disconnecting ringing current from said line and extinguishing said signaling means.

2. In a telephone system, a subscribers line terminating in a line jack at a central oflice, a link circuit, a trunk circuit for interconnecting the subscribers line and link circuit, a source of ringing current associated with the trunk circuit adapted to be impressed upon said subscribers line, signaling means associated with said link circuit operable in a characteristic manner by the ap- The operation of replication of ringing current to said subsoribf ers line, a relay bridged across said link cir-.

cuit, a second relay in said trunk circuit for necting the subscribers line and link 'cir cuit, a source of ringing current ELSSOClfillGd' with the trunk circuit, signaling means as sociated with said link circuit, a relay bridged across said link circuit responsive to the connection of said link circuit and said trunk circuit, a second relay controlled by said first mentioned relay, a third relay in series with said second relay for controlling the application of ringingv current to said trunk circuit, means in said trunk circuit controlled by the application of said ringing current for impressing ringing current from said trunk circuit on said subscribers line, and means in said link circuit including said second relay responsive to the closure of said subscribers line for disconnecting ringing current therefrom and extinguishing said signalingmeans.

4. In a telephone system, a subscribers line terminating in a line jack at a central oflice, a link circuit, a trunk circuit for interconnecting the subscribers line and link circuit, a source of ringing current associated with the trunk circuit adapted to be impressed upon said subscribers line, a relay associated with said link circuit for controlling the application of ringing current to said line, signaling means associated with said link circuit controlled by said relay operable in a characteristic manner by the application of ringing current to said subscribers line, a relay bridged across said link circuit, and a third relay in series with said first relay and controlled by said bridged relay whereby upon the closure of said subscribers line ringing current will be disconnected from said line and said signaling means will be extinguished.

said link circuit, means responsive to the connection of said interrupter for impressing ringing current on said line, signaling means associated with said link circuit operable by the application of ringing current to said line, a second relay serially connected With saidfirst relay whereby upon the closure of said subscribers line ringing current will be disconnected from said line and said si nalin means will be extinguished.

6. Ina telephone system, a subscribers line terminating in a jack at a central ofiice, a link-circuit, a trunk circuit for interconnecting the subscribers line and link circuit, a source of ringing current associated with the trunk circuit, an interrupter, a relay associated with said link circuit for connecting said interrupter to said link circuit, means responsive to the connection of said interrupter for impressing ringing current on said llne, signahng means associated with said link circuit operable in a characteristic manner by the application of ring-- 111g current to said llne, a second relay ser1- v ally connected with said first mentioned relay whereby upon the closure of said sub scribers line ringing current will be disconnected from said line and said signaling means will be extinguished, and a relay bridged across said link circuit whereby upon the opening of said station-line said signaling means will operate as a disconnect signal.

In testimony whereof, I have signed my name to this specification this 5th day of November, 1921.

JOHN F. TOOMEY. 

